This NIH-funded study will evaluate the fasting plasma insulin and proinsulin levels (serially) in the Rochester Diabetic Neuropathy Study Cohort, the Mdewakanton Dakota Native People Study, and the Rocheter Diabetic Neuropathy Study--Healthy Subject Cohort (one time) for the purpose of characterization. The GCRC grant is supporting laboratory tests for insulin and proinsulin levels on the studies conducted at the Prairie Island Indian Reservation and local Rochester population, and therefore we are reporting these as "ancillary only" outpatient visits.